A high-profile Senate investigation into whether the makers of Zero Dark Thirty - the critically-acclaimed film charting the CIA hunt for Osama Bin Laden - were granted “inappropriate access” to classified material has been quietly dropped.

The development came a day after the Katherine Bigelow feature fell flat at the Oscars where many blamed its lack of awards – it picked up just a single technical prize – on the Senate Intelligence Committee investigation and growing controversy over its depiction of the CIA’s alleged use of torture in the search for the al-Qa’ida leader. The committee’s Democratic chair Dianne Feinstein and member John McCain, the former Republican US presidential candidate, had raised concerns about the film’s torture scenes in January.

“Depiction is not endorsement” said Bigelow, who won an Oscar for The Hurt Locker in 2010, as she defended the film against Academy member David Clennon’s calls for a boycott.

When the Oscar nominees were announced on January 10, Bigelow was surprisingly omitted for the best director category. Zero Dark Thirty was nominated for best picture, best original screenwriting, best actress and two editing prizes. It ultimately only won for best sound editing, shared with James Bond film Skyfall.

A congressional aide, speaking anonymously to Reuters, said the Senate intelligence committee had closed its inquiry on Monday. Studio Sony, which produced the film, had no comment.

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